The present invention relates to bifurcated intraluminal grafts, particularly for repairing defects in arteries and other lumens within the body. More particularly, the present invention relates to modular systems for forming bifurcated grafts and to methods for delivering and assembling same in situ for repairing defective body lumens, and particularly abdominal aortic aneurysms.
An abdominal aortic aneurysm is a sac caused by an abnormal dilation of the wall of the aorta as it passes through the abdomen. The aorta is the main artery of the body, supplying blood to all organs and parts of the body except the lungs. It arises from the left ventricle of the heart, passes upward, bends over and passes down through the thorax and through the abdomen, and finally divides into the two iliac arteries which supply blood to the pelvis and lower extremities.
The aneurysm ordinarily occurs in the portion of the aorta below the kidneys. When left untreated, the aneurysm will eventually cause the sac to rupture with ensuing fatal hemorrhaging in a very short time. The repair of abdominal aortic aneurysms has typically required major abdominal surgery in which the diseased and aneurysmal segment of the aorta is removed and replaced with a prosthetic device, such as a synthetic graft.
As with all major surgeries, there are many disadvantages to the foregoing surgical technique, the foremost of which is the high mortality and morbidity rate associated with surgical intervention of this magnitude. Other disadvantages of conventional surgical repair include the extensive recovery period associated with such surgery; difficulties in suturing the graft to the aorta; the loss of the existing thrombosis to support and reinforce the graft; the unsuitability of the surgery for many patients, particularly older patients exhibiting co-morbid conditions; and the problems associated with performing the surgical procedure on an emergency basis after the aneurysm has already ruptured.
In view of the foregoing disadvantages of conventional surgical repair techniques, techniques have been developed for repairing abdominal aortic aneurysms by intraluminally delivering an aortic graft to the aneurysm site through the use of a catheter based delivery system, and securing the graft within the aorta using an expandable stent. Since the first documented clinical application of this technique was reported by Parodi et al. in the Annals of Vascular Surgery, volume 5, pages 491-499 (1991), the technique has gained more widespread recognition and is being used more commonly. As vascular surgeons have become more experienced with this endovascular technique, however, certain problems have been encountered. One problem has been the difficult nature of the procedure. Particularly complex is the step of transferring one leg of the graft from one iliac artery to the other, which requires the careful manipulation of numerous catheters and guide wires. Another problem has been the kinking and/or twisting of the graft both during and after the graft has been implanted. Still other problems relate to the need for accurate preoperative measurements to be made on the morphology of the aneurysm and the surrounding arterial structure, including the length of the aneurysm, the infrarenal aortic length and diameter, the length and diameter of the aorta between the aneurysm and the iliacs, the diameter of the iliacs, and the angle between the iliacs and the aorta. The difficulty in making these measurements accurately and the wide variations in these measurements among patients mandates that the bifurcated grafts be available in a wide range of sizes and configurations.
There therefore exists a need for a bifurcated graft and an implantation method which will overcome the foregoing deficiencies of the prior art. More particularly, there exists a need for a modular graft system which will more accurately accommodate the widely varying arterial sizes in patients, as well as the other size considerations faced by the surgeon. There also exists a need for a method for delivering and implanting a bifurcated graft which avoids the complex procedure for implanting prior art bifurcated grafts.
The present invention addresses the needs.
One aspect of the present invention provides a modular prosthesis for repairing a tubular anatomical structure consisting of a base member foldable radially between a collapsed configuration and an expanded configuration and extending longitudinally between a proximal end and a distal end, a primary tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, and joining means for intraluminally joining the distal end of the primary limb to the proximal end of the base member. Preferably, the joining means includes a friction fit engagement between the distal end of the primary limb in the expanded configuration and the proximal end of the base member in the expanded configuration.
In accordance with one embodiment of the modular prosthesis, the primary limb may have a first diameter at its proximal end and a second diameter less that the first diameter at its distal end. In this regard, the diameter of the primary limb may decrease from the proximal end toward the distal end at an angle of taper between about 2 degrees and about 15 degrees. In preferred embodiments, the primary limb may have a diameter at its proximal end of between about 16 mm and about 36 mm in the expanded configuration and a diameter at its distal end of between about 16 mm and about 25 mm in the expanded configuration. The primary limb may also have a length from its proximal end to its distal end of between about 6 cm and about 15 cm. Desirably, the primary limb includes an annular sleeve at its distal end, the annular sleeve having a substantially uniform diameter. The primary limb may also include securing means at its proximal end for securing the primary limb to the tubular anatomical structure.
The base member may have a first diameter at its proximal end and a second diameter greater than the first diameter at its distal end. In preferred embodiments, the base member may have a diameter at its proximal end of between about 16 mm and about 25 mm in the expanded configuration. The base member may also include an annular sleeve at its proximal end, the annular sleeve having a substantially uniform diameter. Preferably, the annular sleeve has a length between about 2 cm and about 15 cm.
The base member and the primary limb may both consist of a flexible layer which is radially supported along substantially its entire length by an expandable stent. In one embodiment, the expandable stent may be formed from a high shape-memory material. In another embodiment, the expandable stent may be formed from a low shape-memory material.
In accordance with another embodiment hereof, the base member may include dividing means for forming first and second passageways communicating between the proximal and distal ends of the base member. The dividing means may include a line of stitching joining one surface of the base member to an opposite surface of the base member. Alternatively, the dividing means may include a web of material arranged longitudinally inside the base member and defining a first substantially round aperture adjacent the distal end of the base member and a second substantially round aperture at a spaced distance from the distal end of the base member. Preferred embodiments may further include at least one secondary tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, and connecting means for connecting the proximal end of the secondary limb to the distal end of the base member.
In accordance with a further embodiment of the present invention, a modular prosthesis for repairing a tubular anatomical structure consists of a base member foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, a primary tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, joining means for intraluminally joining the distal end of the primary limb to the proximal end of the base member, at least one secondary tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, and connecting means for connecting the proximal end of the secondary limb to the distal end of the base member. The secondary limb may have a substantially uniform diameter of between about 10 mm and about 25 mm in the expanded configuration. Alternatively, the proximal end of the secondary limb may have a diameter which is different than the diameter on its distal end. Preferably, the secondary limb has a length between its proximal end and its distal end of between about 4 cm and about 15 cm.
In this last embodiment, the base member may include a main leg on its proximal end and first and second legs on its distal end. The main leg may extend in an axial direction and have a main passageway extending longitudinally therein and defining an inlet on its free end. The first leg may be oriented at a first angle to the axial direction and have a first passageway extending longitudinally therein and communicating with the main passageway, and may define a first outlet on its free end. The second leg may be oriented at a second angle to the axial direction and have a second passageway extending longitudinally therein and communicating with the main passageway, and the second leg may define a second outlet on its free end. The first angle may be different than the second angle, but each of the first and second angles are preferably between about 10 degrees and about 60 degrees. Also, the main leg may be oriented in a primary plane, and at least one of the first and second legs may be oriented in a plane different than the primary plane.
In a variant of this last embodiment, the base member may include a crotch defined between the first and second legs, the first leg having a length between the crotch and the first outlet of between about 2 cm and about 15 cm. Preferably, the first leg has a substantially uniform diameter of between about 10 mm and about 25 mm in the expanded configuration, and the second leg has a diameter which decreases in size from the second outlet toward the main leg.
This last embodiment may further include another secondary tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, and attaching means for attaching the proximal end of the another secondary limb to the distal end of the base member. The another secondary limb may have a length between its proximal end and its distal end of between about 4 cm and about 15 cm, and a substantially uniform diameter of between about 10 mm and about 25 mm in the expanded configuration. Alternatively, the another secondary limb may have a first diameter at its proximal end and a second diameter at its distal end different than the first diameter.
In yet another embodiment of the present invention, a modular prosthesis for repairing a tubular anatomical structure may consist of a base member extending longitudinally between a proximal end defining an inlet and a distal end defining first and second outlets, the base member being foldable radially between a collapsed configuration and an expanded configuration, and a primary tubular limb having a proximal end and a distal end and being foldable radially between a collapsed configuration and an expanded configuration. The distal end of the primary limb in the expanded configuration may be matable in overlapping circumferential engagement with the inlet of the base member when the base member is in the expanded configuration to join the primary limb to the base member. The modular prosthesis may also include at least one secondary tubular limb having a proximal end and a distal end and being foldable radially between a collapsed configuration and an expanded configuration. The proximal end of the at least one secondary limb may be matable in overlapping circumferential engagement with one of the first and second outlets of the base member when the base member is in the expanded configuration to join the at least one secondary limb to the base member. Another secondary tubular limb may also be provided in which its proximal end is matable in overlapping circumferential engagement with another of the first and second outlets of the base member when the base member is in the expanded configuration to join the another secondary limb to the base member.
Another aspect of the present invention provides a prosthesis for repairing a tubular anatomical structure consisting of a hollow tubular body constructed from a woven fabric and having a length defined between a first end and a second end, the first end having a first diameter and the second end having a second diameter, the body having a diameter intermediate the first and second ends which is less than at least one of the first and second diameters. The first diameter may also be less than the second diameter. The first end of the body may have a diameter between about 16 mm and about 25 mm and the second end of the body may have a diameter between about 16 mm and about 36 mm. The diameter of at least a portion of the body may increase in size at an angle of taper between about 2 degrees and about 15 degrees, preferably at an angle of taper of about 4 degrees. The body may also have a length between about 6 cm and about 15 cm. Preferably, the body also includes an annular sleeve integrally formed at one end, the annular sleeve having a substantially uniform diameter.
Preferred embodiments of this aspect of the present invention may further include an expandable stent assembled to the body and radially supporting the body along substantially the entirety of its length. The expandable stent may be assembled in the interior of the body or on the exterior of the body, and may be formed from a high shape-memory material or from a low shape-memory material.
Yet another aspect of the present invention provides a method for repairing a tubular anatomical structure having a proximal branch and a pair of distal branches projecting from the proximal branch at a point of bifurcation. A method in accordance with this aspect of the present invention may include the steps of providing a first tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, providing a base member foldable radially between a collapsed configuration and an expanded configuration and having an inlet and first and second outlets, and providing a primary tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end. The first limb may be fed in the collapsed configuration through one distal branch until its proximal end is positioned adjacent the point of bifurcation and its distal end is positioned within the one distal branch. The first limb may then be expanded from the collapsed configuration to the expanded configuration whereupon it engages and becomes secured within the one distal branch.
The base member may then be fed in the collapsed configuration through the one distal branch and the first limb until the inlet is positioned in the proximal branch, the first outlet is positioned within the proximal end of the first limb, and the second outlet is at least partially aligned with the other distal branch. The base member may then be expanded from the collapsed configuration to the expanded configuration, whereupon the first outlet engages the proximal end of the first limb in friction fit circumferential contact to join the first outlet of the base member to the first limb.
The primary limb may be fed in the collapsed configuration through one of the distal branches and one of the first and second outlets of the base member until its proximal end is positioned in the proximal branch and its distal end is positioned within the inlet of the base member. The primary limb may then be expanded from the collapsed configuration to the expanded configuration, whereupon its distal end engages the inlet in friction fit circumferential contact to join the primary limb to the inlet of the base member and its proximal end engages and becomes secured within the proximal branch.
Preferred methods may further include the steps of providing a second tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, feeding the second limb in the collapsed configuration through the other distal branch until its proximal end is positioned within the second outlet of the base member and its distal end is positioned within the other distal branch, and expanding the second limb from the collapsed configuration to the expanded configuration, whereupon its proximal end engages the second outlet of the base member in friction fit circumferential contact to join the second limb to the second outlet of the base member and its distal end engages and becomes secured within the other distal branch. The steps of feeding and expanding the second limb may occur prior to the steps of feeding and expanding the primary limb.
Another method in accordance with the present invention may include the steps of providing a base member foldable radially between a collapsed configuration and an expanded configuration and having an inlet and first and second outlets, and providing a primary tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end. The base member may be fed in the collapsed configuration through one of the distal branches until the inlet is positioned in the proximal branch, the first outlet is positioned within the one distal branch, and the second outlet is at least partially aligned with the other distal branch, and expanded from the collapsed configuration to the expanded configuration, whereupon the first outlet engages and becomes secured within the one distal branch. The primary limb may be fed in the collapsed configuration through one of the distal branches and one of the first and second outlets of the base member until its proximal end is positioned in the proximal branch and its distal end is positioned within the inlet of the base member. The primary limb may be expanded from the collapsed configuration to the expanded configuration, whereupon its distal end engages the inlet in friction fit circumferential contact to join the primary limb to the base member and its proximal end engages and becomes secured within the proximal branch.
This last method may further include the steps of providing a first tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, feeding the first limb in the collapsed configuration through the other distal branch until its proximal end is positioned within the second outlet of the base member and its distal end is positioned within the other distal branch, and expanding the first limb from the collapsed configuration to the expanded configuration, whereupon its proximal end engages the second outlet of the base member in friction fit circumferential contact to join the first limb to the second outlet of the base member and its distal end engages and becomes secured within the other distal branch.
A still further method for repairing anatomical structures in accordance with the present invention may include the steps of providing a primary tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, and providing a base member foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end. The primary limb may be fed in the collapsed configuration through one distal branch until it is positioned entirely in the proximal branch, and expanded from the collapsed configuration to the expanded configuration, whereupon it engages and becomes secured within the proximal branch. The base member may be fed in the collapsed configuration through one distal branch until its proximal end is positioned within the distal end of the primary limb, and expanded from the collapsed configuration to the expanded configuration, whereupon its proximal end engages the distal end of the primary limb in friction fit circumferential contact to join the base member to the primary limb. In preferred methods, the step of feeding the base member may include the step of positioning the base member so that its distal end rests upon the point of bifurcation when the base member is joined to the primary limb.
In a variant of this last method, the base member may include first and second passageways providing communication between its proximal and distal ends, and the method may include the further steps of providing a first tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, feeding the first limb in the collapsed configuration through one distal branch until its proximal end is positioned within one passageway of the base member and its distal end is positioned within the one distal branch, and expanding the first limb from the collapsed configuration to the expanded configuration, whereupon its proximal end engages the one passageway of the base member in friction fit circumferential contact to join the first limb to the base member and its distal end engages and becomes secured within the one distal branch. The method may further include the steps of providing a second tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, feeding the second limb in the collapsed configuration through the other distal branch until its proximal end is positioned within the other passageway of the base member and its distal end is positioned within the other distal branch, and expanding the second limb from the collapsed configuration to the expanded configuration, whereupon its proximal end engages the other passageway of the base member in friction fit circumferential contact to join the second limb to the base member and its distal end engages and becomes secured within the other distal branch.
Yet a further method for repairing a tubular anatomical structure in accordance with the present invention may include the steps of providing a component foldable radially between a collapsed configuration and an expanded configuration and having a proximal end with a first diameter, a distal end with a second diameter, and a diameter intermediate its proximal and distal ends which is less than at least one of the first and second diameters. The component may be fed in the collapsed configuration through one distal branch until it is positioned entirely in the proximal branch, and expanded from the collapsed configuration to the expanded configuration, whereupon the component engages and becomes secured within the proximal branch.
In this last method, the component may include first and second passageways providing communication between its proximal and distal ends, and the method may include the added steps of providing a first tubular limb foldable between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, feeding the first limb in the collapsed configuration through one distal branch until its proximal end is positioned within one passageway of the component and its distal end is positioned within the one distal branch, and expanding the first limb from the collapsed configuration to the expanded configuration, whereupon its proximal end engages within the one passageway of the component in friction fit circumferential contact to join the first limb to the component and its distal end engages and becomes secured within the one distal branch. Preferred methods may further include the steps of providing a second tubular limb foldable radially between a collapsed configuration and an expanded configuration and having a proximal end and a distal end, feeding the second limb in the collapsed configuration through the other distal branch until its proximal end is positioned within the other passageway of the component and its distal end is positioned within the other distal branch, and expanding the second limb from the collapsed configuration to the expanded configuration, whereupon its proximal end engages within the other passageway of the component in friction fit circumferential contact to join the second limb to the component and its distal end engages and becomes secured within the other distal branch.
The modular graft system and surgical methods of the present invention overcome many of the difficulties associated with delivering and securing the bifurcated grafts of the prior art. By providing a graft in the form of modular components that can be individually selected and assembled together, the present invention permits more accurate sizing of the graft to the individual patient. Moreover, the modular system forms grafts having a fully supported structure which is much stronger than the prior art grafts and which obviates the prior art procedures in which the graft is secured by hanging at the proximal neck of the aneurysm, which arrangement is prone to acute and chronic failure whereby the graft could become displaced or collapsed. The modular system of the present invention further takes advantage of the flow of blood through the individual components to lock the components to one another, thereby assuring a secure assembly and minimizing the possibility of leakage.